From Keith Morris
In the article on moon dust Dana Mackenzie writes that Harrison Schmitt of Apollo 17 reported hay fever-like symptoms on his return journey (28 May, p 40). When I was an engineer in a South African vanadium plant in the 1970s, I experienced flu-like symptoms, and discovered that dust from the purification process was the cause. Perhaps finely powdered metallic elements in moon dust have a similar effect.
Grove, Oxfordshire, UK
